Lubica Stuchlikova

Investigation of deep energy levels in heterostructures based on GaN by DLTS

In this paper we report our results of DLTS investigations of deep-level defects in Schottky-gate AlGaN/GaN LP-MOVPE structures grown on sapphire substrate. The exact location of heterostructures interface below the surface (20 nm) was determined from the concentration profile to depletion region width dependence. The free charge carrier density was calculated (n<inf>2D</inf> = 4.75÷5.09×10¹⁶ m⁻²). Four deep energy levels have been identified from selected DLTFS spectra (activation energies: E1=E<inf>C</inf>−0.545 eV, E2=E<inf>C</inf>−0.599 eV, E3=E<inf>C</inf>−0.642 eV, and E4=EC-1,118 eV).

Massive open online courses in microelectronics education

A massive open online course (MOOC) is a model for delivering learning content online with no limit on attendance to any person who expresses interest. This paper highlights the challenges, advantages and rewards of the MOOC model in microelectronics education. The authors are focusing on the practical experiences acquired in design and realization of MOOC located on an educational portal called “eLearn central” based on LMS Moodle.

4H-SiC Diode with a RuOx and a RuWOx Schottky Contact Irradiated by Fast Electrons

The impact of radiation damage on the device performance of 4H-SiC Schottky diodes with a RuO2 and a RuWOx Schottky contacts, which were irradiated at room temperature with 9 MeV electrons (absorbed dose of 50 gy), is studied. No degradation is observed from measured capacitance-voltage curves. The radiation-induced decrease of the Schottky barrier height is observed from current-voltage measurements. Eight electron deep energy levels are observed before irradiation, and eighteen electron levels are induced after irradiation by a standard deep level transient spectroscopy

DLTFS study of InGaAs/AlInAs heterostructures grown on n-InP:S substrates

In this paper authors are presenting the first results of electrically active defect investigations in the three 5×UD-In0.53Ga0.47As/Al0.42In0.58As MQW structures grown on n-InP:S substrates by low pressure metal organic vapour phase epitaxy at same growth conditions but at different growth rates. The defect distribution is different for each sample. As thinner are the quantum well layers as more significant minority carrier responses are measured. Parameters of nine deep energy levels were identified by Deep Level Transient Fourier Spectroscopy method. The three of them T3 (~0.38 eV), T5 (~0.17 eV) and T7 (~0.32 eV) were identified in all investigated structures. We assume that level T1 (~0.19 eV) and T5 (0.17 eV) are with high probability the result of carrier emissions from QWs.

Interactive animation as a motivation tool

This article highlights the practical experiences acquired in design, realization and implementation of interactive animations for students, located at “eLearn central” an educational portal based on LMS Moodle. Interactive animation presenting a unique motivation tool, in education, increases the interest of students by online communication, illustrative explanations and controlled content. The aim of this work is to attract attention by freely available visualizations and animations, thereby to increase the efficiency of education and to motivate users for further studies.

Challenges of education in the 21st century

The technological environment of the 21st century has a direct impact on education. Although our main domain is university education, we have to look more complexly on issues of basic education as well. Primary and secondary schools are our partners in common goal of raising experts for the future. Children, who start to attend schools today, will be employed as high skilled experts in 2034. We have no exact idea what kind of conditions, level of science and technology awaits them. Since we cannot predict the future, we should at least try to adapt teaching nowadays. Our basic task is to lead students to think critically, to work with high adaptability and flexibility and to support their individuality and creativity. Last but not least to increase intrinsic motivation of them about knowledge and learning of new ones. This article highlights the challenges of education in the 21st century. In the world we can see interesting solutions of these challenges, dealt with in today and future situations of education in Slovakia. Facing some of these challenges author sees the solution in effective application of information and communications technologies (ICT) and new pedagogical approaches.

Investigation of AlGaN/GaN Schottky structures by deep level fourier transient spectroscopy with optical excitation

This paper highlights electrical characterization of Schottky structures prepared on AlGaN/GaN designed for HEMTs using Deep Level Transient Fourier Spectroscopy (DLTFS) method with electrical and optical excitation. In case of electrical excitation the density of minority and majority carrier traps had strong effect on the evaluation, whereas preliminary DLTFS with optical excitation (MCDLTFS) measurements made possible to identify minority carrier defects with higher precision. Parameters of two electron-like defects EL1 (0.47 eV), EL2 (0.54 eV) and three hole-like defects HL1 (1.13 eV), HL2 (0.93 eV) and HL3 (0.49 eV) were identified. HL1 andHL2 were confirmed by both methods: DLTFS and MCDLTFS. These are connected to a Carbon interstitial defect and well-know threading dislocations. Experimental results confirmed the benefits of different method utilizations in complex defect identifications.

Impact of repetitive UIS on modern GaN power devices

In this paper we present the results from repetitive Unclamped Inductive Switching - UIS measurements on power GaN HEMTs. Experimental analysis was performed on two types of power devices - normally ON and OFF HEMTs. UIS test was used to simulate real switching conditions in which power device has to operate. Analysis has shown that charge trapping effects on interfaces and in bulk layer have strong impact on electrical performance of devices. DLTS study was performed on virgin and short and long stressed sample for better understanding of trapping effects.

Study of repetitive avalanche stress invoked degradation of electrical properties of DMOS and TrenchMOS transistors

An electrical ageing of three power MOS transistor types has been performed in order to investigate the gradual degradation in time (number of stress pulses) of the static electrical parameters. It is attributed to hot carrier injection in the space charge region of drain - P well blocking PN junction and involves different complex mechanisms mainly defects generation/activation in the drain side region of the gate oxide and near the oxide/silicon interface. Charge of defects leads to shift of electrical characteristics and parameters. The devices used in this experiment were low voltage vertical power DMOS transistor rated to 24 V and TrenchMOS transistors rated to 30 V.

How to prepare university graduates as highly skilled key enabling technologies professionals

Key Enabling Technologies represent the background of a greener economy and Europes industrial modernization. High quality preparation of great number of highly skilled Key Enabling Technologies professionals is essential for the future economic growth, competitiveness and innovation of Europe. This article presents experiences acquired by long term involvement of the Institute of Electronics and Photonics, Slovak University of Technology in Bratislava, in training Key Enabling Technologies professionals. Authors focused their attention on selected examples of available effective tools to prepare highly skilled university graduates.